The present invention relates to a color cathode-ray tube. More to particularly, this invention relates to structure of a shadow mask electrode and a shadow mask electrode supporting body which influence picture quality of the color cathode-ray tube.
In the color cathode-ray tube, the greater parts of electron beam meet a shadow mask electrode. Accordingly, temperature of the shadow mask electrode rises. Temperature rise deforms shadow mask electrode caused by thermal expansion. Picture quality deterioration occurs according to this deformation. It is necessary to prevent picture quality deterioration caused by the deformation. In order to prevent the picture quality deterioration, formerly, fixed tension is applied to the shadow mask electrode. The shadow mask electrode is fastened to a frame while applying fixed tension thereto.
In recent years, requirement with respect to picture quality becomes increasingly severe. For that reason, metal whose coefficient of thermal expansion is low such as Invar is used so that it is capable of reducing thermal expansion of the shadow mask electrode itself to the utmost.
Above-mentioned conventional techniques are combined with each other. Namely, the shadow mask electrode is made of metal such as Invar whose coefficient of thermal expansion is low. Tension is applied to the shadow mask electrode made of Invar in order to fasten it flatly to a supporting body. A frame body is made of the same metal as that of the shadow mask electrode. The shadow mask electrode is fastened to the frame body while applying fixed tension thereto. The thermal expansion rate of shadow mask electrode agrees with the thermal expansion rate of the frame body. It is capable of obtaining a color cathode-ray tube with very excellent picture quality.
However, the metal whose thermal expansion rate is low is very expensive. It is very expensive when the frame body is made of the metal with low thermal expansion rate. It is not practical. Consequently, as a practical method, the shadow mask electrode is made of metal whose thermal expansion rate is low such as Invar and so forth but expensive. The frame body is made of metal whose thermal expansion rate is high such as steel and so forth but cheap. Thus it can be considered that the shadow mask electrode made of metal with low rate of thermal expansion is combined with the frame body made of metal with high rate of thermal expansion.
However, such combination brings picture quality deterioration. The combination between the shadow mask electrode and the frame body with difference of thermal expansion rate described above brings difference of expansion and contraction between the shadow mask electrode and the frame body. Such combination brings shears, wrinkles, slackening and so forth from design dimension of the shadow mask electrode. Such wrong condition occurs either in temperature (about 400 to 500xc2x0 C.) during manufacturing of color cathode ray tube, and in temperature (about 50 to 100xc2x0 C.) in use of the color cathode ray tube.
In view of the foregoing, it is an object of the present invention, in order to overcome the above-mentioned problems to provide a color cathode-ray tube which provides constitution both of a shadow mask electrode and a frame body in which difference of expansion and contraction between the shadow mask electrode and the frame body does not produce picture quality deterioration with practical cost.
In accordance with a first aspect of the present invention, in order to achieve the above mentioned object, there is provided a color cathode-ray tube which comprises a shadow mask electrode made of metal whose thermal expansion rate is low and to which tension is applied to be flatly supported, a color electrode supporting body made of metal whose thermal expansion rate is approximately the same as that of the shadow mask electrode, for supporting shadow mask electrode, and a frame body made of metal whose thermal expansion rate is different from that of the shadow mask electrode, for supporting the shadow mask electrode supporting body.
According to the first aspect, the shadow mask electrode and the shadow mask electrode supporting body are made of approximately the same metal whose thermal expansion rate is low. Relative difference of dimension between the shadow mask electrode and the shadow mask electrode supporting body is small in relation to temperature change. It is capable of preventing picture quality deterioration caused by shear, wrinkle, or slackening from design dimension of the shadow mask electrode in use or during manufacturing of the color cathode-ray tube. Further, the frame body is made of metal whose price is low, thus it is capable of constituting the color cathode ray tube in low cost.
In accordance with a second aspect of the present invention, in the first aspect, there is provided a color cathode-ray tube wherein tension in one-way direction is applied to the shadow mask electrode to be flatly supported.
As described-above according to the second aspect, since the tension in one-way direction is applied to the color section electrode, it is capable of being prevented the picture quality deterioration caused by shear, wrinkle, or slackening of the shadow mask electrode due to stress-strain convergence at the corner part of the shadow mask electrode.
In accordance with a third aspect of the present invention, in the second aspect, there is provided a color cathode-ray tube, wherein tension in one-way direction is applied to the shadow mask electrode to be flatly supported, and there is provided the shadow mask electrode supporting body for only two sides which stand opposite each other for applying tension to said shadow mask electrode.
As described above, according to the third aspect, since there is provided a color cathode-ray tube, wherein tension in one-way direction is applied to the shadow mask electrode to be flatly supported, and there is provided the shadow mask electrode supporting body for only two sides which stand opposite each other for applying tension to said shadow mask electrode. Thus, it is capable of prevented the picture quality deterioration caused by shear, wrinkle, or slackening of the shadow mask electrode due to stress-strain convergence at the corner part of the shadow mask electrode.
In accordance with a fourth aspect of the present invention, a color cathode-ray tube which comprises a shadow mask electrode made of metal whose thermal expansion rate is low and to which tension in one-way direction is applied to be flatly supported, color electrode supporting bodies consisting of different kind of metals, one metal whose thermal expansion rate is approximately the same as that of the shadow mask electrode for supporting shadow mask electrode in one-way direction, and the other metal whose thermal expansion rate is different from that of the shadow mask electrode does not support the shadow mask electrode, and a frame body made of metal whose thermal expansion rate is different from that of the shadow mask electrode, for supporting the shadow mask electrode supporting body.
As described-above according to the fourth aspect, since the shadow mask electrode supporting body which does not apply tension to the shadow mask electrode is made of metal whose thermal expansion rate is different from that of the shadow mask electrode, the shadow mask electrode is made of metal whose price is low resulting in cost down.
In accordance with a fifth aspect of the present invention, there is provided a color cathode-ray tube which comprises a shadow mask electrode made of metal whose thermal expansion rate is low and to which tension in one-way direction is applied to be flatly supported, color electrode supporting bodies made of metal whose thermal expansion rate is approximately the same as that of the shadow mask electrode for supporting shadow mask electrode in one-way direction, and a frame body made of metal whose thermal expansion rate is different from that of the shadow mask electrode, for supporting the shadow mask electrode supporting body, and whose extended part comes into contact with the shadow mask electrode in different part from one-way direction supported part in order to support it.
As described-above, according to the fifth aspect, sides of the shadow mask electrode, which tension is not applied are supported by extended part of the frame body, thus structure of the frame is more simplified further resulting in cost down.
In accordance with a sixth aspect of the present invention, in any of the first to fifth aspects, there is provided a color cathode-ray tube, wherein shape of the shadow mask electrode is plane.
As described above, according to the sixth aspect, it is capable of realizing plane type color cathode-ray tube whose image is easy to see and without distortion because shape of the shadow mask electrode is plane.
In accordance with a seventh aspect of the present invention, in any of the first to fifth aspect, there is provided a color cathode-ray tube, wherein shape of the shadow mask electrode is a part of side surface of a cylinder.
As described-above, according to the seventh aspect, it is capable of realizing the color cathode-ray tube which is easy to see and a low cost because shape of the shadow mask electrode is a part of cylinder side face.
In accordance with an eighth aspect of the present invention, in any of the first to seventh aspect, there is provided a color cathode-ray tube, wherein shape of the frame body is rectangular.
As described-above, according to the eighth aspect, the structure of the frame body is simplified to be miniaturized thus resulting in light weight.
In accordance with a ninth aspect of the present invention, in any of the first to the eighth aspect, there is provided a color cathode ray tube, wherein the frame body is approximately rectangular with section which a part of section and/or the whole of section is L-shape.
As described-above, according to the ninth aspect, the frame body is miniaturized to be light weighted because distortion resistance becomes high because the frame body is approximately rectangular with section which a part of section and/or the whole of section is L-shape.
In accordance with a tenth aspect of the present invention, in any of the first to eighth aspect, there is provided a color cathode-ray tube, wherein the frame body has approximately rectangular with section which a part of section and/or the whole of section is L-shape, and there are provided embosses in a part of said frame body and/or in the whole of said frame body.
As described-above, according to the tenth aspect, the frame body is difficult to be deformed because the frame body has approximately rectangular with section which a part of section and/or the whole of section is L-shape, and there are provided embosses in a part of said frame body and/or in the whole of said frame body. The frame body is miniaturized and lightened.
In accordance with an eleventh aspect of the present invention, in any of the first to eighth aspect, there is provided a color cathode-ray tube, wherein the frame body has rectangular shape with section which a part of section and/or the whole of section is triangular shape.
As described-above, according to the eleventh aspect, the frame body is difficult to be deformed because the frame body has approximately rectangular with section which a part of section and/or the whole of section is triangular shape, and there are provided embosses in a part of said frame body and/or in the whole of said frame body. The frame body is miniaturized and lightened.
In accordance with a twelfth aspect of the present invention, in any of the first to eighth aspect, there is provided a color cathode-ray tube, wherein there is provided a reinforcing member on a part of the frame body and/or the whole of the frame body.
As described-above, according to the twelfth aspect, there is provided a color cathode-ray tube wherein the frame body is difficult to be deformed because the frame body has approximately rectangular with section which a part of section and/or the whole of section is provided with reinforcing member. The frame body is miniaturized and lightened.
In accordance with a thirteenth aspect of the present invention, there is provided a color cathode-ray tube, wherein a part of the frame body and/or the whole of said frame body is manufactured by stamping out press processing.
As described-above, according to the thirteenth aspect, it is capable of manufacturing the frame body with short time and low cost because a part of the frame body and/or the whole of said frame body is manufactured by stamping out press processing.
In accordance with a fourteenth aspect of the present invention, there is provided a color cathode-ray tube, wherein a shape of two sides which stand opposite each other and to which tension is applied is different from a shape of the two sides which stand opposite each other and to which no-tension is applied.
As described-above, according to the fourteenth aspect, since it causes a shape of two sides which stand opposite each other and to which tension is applied to be different from a shape of the two sides which stand opposite each other and to which no-tension is applied. It is capable of executing a scheme closely for the sake of intention reinforcing for the former requiring intensity, while it is capable of simplifying intention reinforcing for the former which requires weak intensity in comparison with the later. It is capable of executing cost down, miniaturization, and/or light weighing of the frame body.
In accordance with a fifteenth aspect of the present invention, there is provided a color cathode-ray tube, wherein the shadow mask electrode and the shadow mask electrode supporting body which applies tension to the shadow mask electrode are made of nickel-iron alloy including nickel of 34% to 40% and a slight amount of addition elements, and the frame body and the shadow mask electrode supporting body which applies no-tension to the shadow mask electrode are made of steel and/or stainless steel.
As described-above, according to the fifteenth aspect, the shadow mask electrode and the shadow mask electrode supporting body which applies tension to the shadow mask electrode are made of nickel-iron alloy including nickel of 34% to 40%, and the frame body and the shadow mask electrode which applies no-tension to the shadow mask electrode are made of steel and/or stainless steel. Therefore, it is capable of preventing picture quality deterioration because of low thermal expansion rate. The shadow mask electrode and the shadow mask electrode supporting body which applies tension to the shadow mask electrode have the same low thermal expansion rate. Further, the frame body and the shadow mask electrode which applies no-tension to the shadow mask electrode are difficult to be deformed enabling sufficient tension to be applied to the shadow mask electrode. Thus it is capable of realizing the color cathode-ray tube whose picture quality is very excellent with a low cost according to the synergistic effect thereof.
The above and further objects and novel features of the invention will be more fully understood from the following detailed description when the same is read in connection with the accompanying drawings. It should be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the invention.